Combustion
Combustion
researchers rely on laser-based optical diagnostic
techniques as essential tools in understanding and
improving the combustion process. For example, a
majority of researchers use the quantitative
data from planar laser-induced fluorescence (PLIF)
techniques in order to study various processes, such
as internal combustion engines and hypervelocity
combustion.
.
Laser-Induced Fluorescence in
Combustion
In
Laser-Induced Fluorescence (LIF), an
atom or molecule gets excited by the absorption of
a laser photon. When the atom falls back into the
ground state after a certain time (typically 1-100nsec),
it undergoes radiative emission, known as fluorescence.
Since the fluorescence intensity is dependent on
parameters such as ground state population, chemical
environment, pressure, and temperature, laser-induced
fluorescence measurements have become a vital tool
in physical chemistry. For example, some applications
include the investigation of elementary chemical
reactions and trace analytics down to sub-ppm
concentrations. In combustion diagnostics, LIF measurements
(also called PLIF in planar illumination) are
widely utilized. They allow for the qualitative and
quantitative detection of flame radicals and combustion
intermediates such as OH, C2, CH, CH2O,
as well as pollutants like NO and
CO.
PLIF Instrumentation
In
a simple PLIF setup, a thin sheet of laser (typically
a pulsed laser) illuminates a flame or flow field. The
resulting fluorescence from the radicals is detected
by a gated intensified CCD while the excitation is
eliminated using a band pass filter. The spatial,
temporal, and intensity information of the fluorescence
is useful in engine diagnostics techniques for the
measurement of local fuel concentrations and temperature
distributions. Although naturally occurring chemical
species are often used in PLIF measurements, external
tracer particles are also occasionally added to create
a fluorescence signal.
Simplified PLIF setup
Combustion Research
and Princeton Instruments
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For over two decades, PI
has actively developed solutions for the
combustion community, beginning with PI-MAX,
the first high-performance, gated ICCD camera.
Coupled with spectrograph solutions from
Acton Research, PI provides some of the most
comprehensive diagnostic tools for combustion. |
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NEW - PI-MAX 3: 1024i camera with near video rate frame rate. Ideal to synchronize with fast repitition rate lasers.
- World's first ICCD camera
with >25% QE in 300nm region and < 9 nsec
gating capability for OH-PLIF (PI-MAX:SB)
-
Dual-image capability for
PIV applications (CoolSNAP-HQ, PI-MAX 3: 1024i)
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Integrated, full programmable
timing generator (PTG in PI-MAX) and SuperSYNCHRO (in PI-MAX 3) for easy synchronization.
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Recommended Products
ProEM - Professional-Grade EMCCD Cameras
PI-MAX 3 - Faster, Smarter ICCD Cameras
PI Cameras in Combustion:
NASA Tech Briefs
Optics Letters
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